Medical treatment of several illnesses requires continuous drug infusion into various body compartments, such as subcutaneous and intra-venous injections. Diabetes mellitus (DM) patients, for example, require the administration of varying amounts of insulin throughout the day to control their blood glucose levels. In recent years, ambulatory portable insulin infusion pumps have emerged as a superior alternative to multiple daily syringe injections of insulin, initially for Type 1 diabetes patients and subsequently for Type 2 diabetes patients. These pumps, which deliver insulin at a continuous, or periodic, basal rate as well as in bolus volumes, were developed to liberate patients from repeated self-administered injections, and allow them to maintain a near-normal daily routine. Both basal and bolus volumes must be delivered in substantially precise doses, according to individual prescription, because an overdose or under-dose of insulin could be fatal.
The first generation of portable insulin pumps includes “pager like” devices, each with a reservoir contained within a rigid case housing. The reservoir is usually a syringe barrel and reservoir filling is performed by drawing replenishing therapeutic fluid from a vial with a complementary adapter. After filling the reservoir, the syringe handle (plunger rod) is disconnected and disposed of, and the barrel (reservoir) is placed within the rigid case housing. The proximal end of the reservoir is engaged with a driving mechanism and its distal end is connected to an infusion set (tubing). Examples of such devices are disclosed, for example, in U.S. Pat. Nos. 3,631,847, 3,771,694, 4,657,486 and 4,544,369, the contents of all of which are hereby incorporated by reference in their entireties. These devices represent an improvement over the application of multiple daily injections, but suffer from some drawbacks, among which are the devices' relatively large size, weight, and long tubing.
To avoid the limitations of first generation infusion pumps, a new concept was proposed, which was implemented in second generation pumps. The new concept concerns a remote controlled skin adherable device with a rigid case housing having a bottom surface adapted to be in contact with the patient's skin. The reservoir is contained within the rigid case housing and reservoir filling is performed with an additional syringe that is used to draw the replenishing therapeutic fluid (the drug) from a vial with an injection needle that is also adapted to be in fluid communication with the reservoir. This approach is described, for example, in U.S. Pat. Nos. 4,498,843, 5,957,895, 6,589,229, 6,740,059, 6,723,072 and 6,485,461, the contents of all of which are hereby incorporated by reference in their entireties. These second generation skin adherable devices also have several drawbacks including, for example, the fact that an entire second-generation device, including all the expensive components (electronics, a driving mechanism, etc.), has to be disposed of every 2-3 days.
Third generation skin-adherable devices were developed to avoid the cost issues of second generation devices and to extend patient customization. An example of such a device is described in co-owned/co-pending U.S. patent application Ser. No. 11/397,115 (Publication No. 2007/0106218), the content of which is hereby incorporated by reference in its entirety. Such a third generation device includes a remote control (also referred to as a remote control unit and/or a remote controller) and a skin-securable (e.g., adherable) dispensing unit (also referred to as a patch and/or a patch unit) that includes two parts: (1) a reusable part containing the electronics, at least a portion of the driving mechanism and other relatively expensive components, and (2) a disposable part containing, for example, the reservoir and/or relatively inexpensive components.
A skin-securable fluid delivery device to deliver therapeutic fluid (e.g., insulin) is disclosed, for example, in co-owned/co-pending U.S. patent application Ser. No. 11/989,681, filed Jul. 24, 2007, and claiming priority to U.S. Provisional Patent Applications Nos. 60/833,110, filed Jul. 24, 2006, and 60/837,877, filed Aug. 14, 2006, both of which are entitled “Systems, Devices, and Methods for Fluid/Drug Delivery”, the contents of all of which are hereby incorporated by reference in their entireties.
A fourth generation infusion device was developed that includes a dispensing unit that can be disconnected and reconnected to a skin-adherable cradle unit (also referred to as a cradle) and may be operated by a user interface (an interface that includes, for example, buttons/switches) located, for example, on the reusable part. Such a fourth (4th) generation device is described, for example, in: I) co-owned/co-pending U.S. patent application Ser. No. 12/004,837 (Publication No. 2008/0215035), filed Dec. 20, 2007, claiming priority to U.S. Provisional Patent Application No. 60/876,679, filed Dec. 22, 2006, entitled “Systems, Devices, and Methods for Sustained Delivery of a Therapeutic Fluid”, the contents of which are hereby incorporated by reference in their entireties; 2) co-owned/co-pending International Patent Application No. PCT/IL08/001001 (Publication No. WO2009/013736), filed Jul. 20, 2008, claiming priority to U.S. Provisional Patent Application No. 60/961,527, and entitled “Manually Operable Portable Infusion Pump”, the contents of which are hereby incorporated by reference in their entireties; and 3) co-owned/co-pending International Patent Application No. PCT/IL08/001057 (Publication No. WO2009/016636), filed Jul. 31, 2008, claiming priority to U.S. Provisional Applications Nos. 60/963,148 and 61/004,019, and entitled “Portable infusion device with means for monitoring and controlling fluid delivery”, the contents of all of which are hereby incorporated by reference in their entireties.
Third (3rd) and fourth (4th) generation dispensing units may be equipped with an analyte (i.e. glucose) sensor to enable continuous (or near-continuous) and/or periodic measurements/readings of analyte levels. Fluid dispensing may thus be performed automatically according to analyte sensing (closed loop system) or performed semi-automatically if the user wishes to have some control of the delivery operations (e.g., open loop system). A fourth (4th) generation sensing and dispensing device is described, for example, in co-owned/co-pending U.S. patent application Ser. No. 11/706,606 (Publication No. 2007/0191702), the content of which is hereby incorporated by reference in its entirety.
An example of a pumping mechanism of third (3rd) and fourth (4th) generation two-part skin-securable dispensing units is a “syringe-like mechanism”. A plunger (piston) is configured to slide within a barrel (reservoir), thus pushing the drug outwardly. The plunger is displaced by, for example, a threaded rod (plunger rod) that can be rigidly connected to the plunger or articulately interact with the plunger and rotate freely. The threaded plunger rod may also used to backwardly slide the plunger during reservoir filling. After filling, the disposable part that contains the reservoir and the outlet port is connected to the reusable part.
Unlike first (1g) and second (2″d) generation pumps, the reservoir may not be protected within a rigid case housing because the reservoir walls correspond to at least a part of the walls of the disposable part, and neither is contained within an additional protective rigid case housing. Such an unprotected reservoir could endanger the user if a high force or impact is directly applied to the dispensing unit and the reservoir walls, thus causing drug overflow (and consequently overdose).